[gpaw-users] Cu2O dipole corrections - convergence problems

[Isabela Man]

Indeed  it was the problem with my script. Now it works. Later on we will
do the update  to the latest version.

Thank you
Isabela


2012/2/20 Jens Jørgen Mortensen <jensj at fysik.dtu.dk>

> On 17-02-2012 14:52, Isabela Man wrote:
> > Dear all,
> > I am trying to do some calculations on different Cu2O surfaces (100,
> > 110, 111 surfaces and for each different surface terminations).
> > For all cases I encounter the same problem. When I do not apply dipole
> > corrections , everything is fine and I get the convergence. When I
> > apply it, depending on surface after none, one or two steps the energy
> > become positive.
> >
> > mixer=Mixer(0.1, 5, weight=100.0)
> > calc = GPAW(h=0.2,
> > xc='RPBE',
> > txt=outid,
> > kpts=(2,2,1),
> > #eigensolver='cg',
> > width=0.10,
> > #verbose=True,
> > mixer=mixer,
> > nbands = -30,
> > spinpol = False,
> > usesymm = False)
> > poissonsolver = PoissonSolver()
> > correction = DipoleCorrection(poissonsolver, 2) # 2 == z-axis
> > calc = GPAW(poissonsolver=correction)
> > calc.attach(calc.write,1,gpwdat)
> > slab.set_calculator(calc)
> >
> > I have attached also a part of the output file and the corresponding
> > structure.
> > I haven't tried yet to run first in the LCAO mode and than to continue
> > this way.
>
> I see one problem in your script:  First, you make a GPAW calculator
> instance "calc=GPAW(...)" and then later you make another one:
>
> calc = GPAW(poissonsolver=correction)
>
> This will overwrite the first one, the one with all the parameters:
> RPBE, mixer, number of k-points, ....  So, you are doing a calculation
> with a dipole correction, but with default parameters: LDA, Gamma point
> only ...
>
> You should do this:
>
> calc=GPAW(xc='RPBE', ..., poissonsolver=correction)
>
> I tried to do that and things converged nicely for me, but that was with
> the development version of GPAW.  I think Ask has fixed a couple of
> problems with the dipole correction since the version of GPAW that you
> are using.  Try updating to the latest version - it should be compatible
> with the version you have, but you better verify that yourself.
>
> Jens Jørgen
>
> >
> > Thank you
> > Isabela Man
>
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